I-75 connection to M-72 as well as access from both directions to Hartwick Pines State Park. Crossing into southern Otsego County, I-75 continues northward through Northern Michigan forests. It passes to the east of the community of Waters and Otsego Lake. North of exit 279, I-75 proceeds by the Gaylord Regional Airport and crosses the 45th Parallel, the halfway mark between the Equator and the North Pole by latitude. The freeway then traverses the west side of Gaylord and continues through forests in the northern sections of the county. North of Vanderbilt, I-75 enters southern Cheboygan County, assuming the G. Mennen Williams Freeway name. I-75 continues northward through Cheboygan County, passing the community of Indian River and spanning the river of the same name. North of town, the freeway traverses the area between Burt and Mullett lakes before intersecting the southern end of M-27; that highway provides access to Topinabee and Cheboygan. I-75 continues northward through tree farms and other agricultural properties in rural Cheboygan County. Cheboygan is accessible by way of interchanges for C-64 and C-66, a pair of county-designated highways in this area. North of C-66, I-75 turns northwesterly. The freeway meets the northern end of US 31 and picks up the Lake Michigan Circle Tour (LMCT) designation before entering Emmet County on the south side of Mackinaw City. I-75 then parallels the county line on the west side of the village, meeting the northern end of US 23. After that interchange, the Lake Huron Circle Tour (LHCT) merges in from the south. There is one more interchange along the freeway before I-75 ascends the approaches to the Mackinac Bridge. Mackinac Bridge The Mackinac Bridge carries I-75 across the Straits of Mackinac that separate Michigan's Upper and Lower peninsulas; the straits also form the connection between Lakes Michigan and Huron. The structure, unlike the rest of the state highways in Michigan like I-75, is under the maintenance and control of the Mackinac Bridge Authority (MBA). The authority collects a toll from traffic that crosses the bridge, which , is $4 for passenger cars and $5 per axle for commercial vehicles and motorhomes. In addition to cash, the MBA offers a pre-paid debit card option for the payment of tolls and accepts credit cards at the toll booths. The authority also provides a driver assistance program that will drive vehicles across the bridge at no additional charge; motorists who